Small hand-held microscopes have been developed for self-observation of salivary ferning patterns to detect the fertile time of a woman’s menstrual cycle. The purpose of this study was to evaluate one such microscope, the Lady Free Biotester®, by comparing it with the self-observation of cervical-vaginal mucus and with the self-detection of luteinizing hormone (LH) in the urine. Twelve natural family planning teachers (average age 34.6 years) observed their cervical-vaginal mucus, tested their urine for LH, and observed salivary and cervical-vaginal mucus ferning patterns (with the Lady Free Biotester) for two menstrual cycles. Data indicated that there was a strong correlation between the LH in the urine and the peak in self-observed cervical-vaginal mucus ferning (r = 0.99, p

NOTICE: this is the author’s version of a work that was accepted for publication in "Contraception." Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Contraception, VOL 57, ISSUE 5, May 1998. DOI.